In an integrated circuit chip, the various functions performed by the logic elements on the chip are dependent on variations in chip operating conditions. These chip operating conditions include the chip operating temperature. Chips are often contained in enclosures which experience extreme variations in temperature that can lead to poor chip performance or even chip failure.
When a chip fails to perform properly or crashes, any one of a variety of factors could be the cause. In order to determine the exact cause of a chip failure, complex recorders may be used to store information on the operating state of the chip before the failure. These recorders can store specific information on the chip temperature, chip operating voltages and other process variables. However, this may require the use of complex analog sensors or fast analog-to digital (A/D) converters which can detect and report the status of these variables on a real time basis. These recorders may also store the states in various registers located on the chip at predetermined intervals.
A drawback with such recorders is the large amount of space that they consume on the chip and the increased amount of processing necessary to continually update the status of all the variables. Another drawback is that analog sensors are often sensitive to noise caused by digital switching operations and other factors. Additionally, the cost of such recorders with a number of analog sensors increases with the complexity of the particular device.
Hence, a need exists for providing a temperature monitor that can monitor the temperature conditions of the chip itself without requiring extensive processing or memory space. It additionally is desirable to provide a temperature monitor using digital logic elements that can be updated based on current chip conditions and can be integrated into a digital design.